In the petroleum industry large quantities of pipes, such as casing, tubing and drill pipes with possible additional equipment, are used in the drilling, completion and maintenance of wells. Said pipes normally come with protective caps of i. a. rigid plastic, screwed on/into external/internal threaded portions at the pipe ends. During installation, or during subsequent dismantling of the pipes on the site of use, it has been common, until today, that the protective caps are unscrewed, or screwed on, by. hand. The work of such manual unscrewing/screwing on of the protective caps is highly time-consuming. Therefore, it is not uncommon that several days are spent on unscrewing protective caps when a large series of pipes are to be run into a well, for example. Moreover, such manual unscrewing/screwing on is considered by most people as a not very meaningful operation.

In many cases the protective caps sit so tight that they cannot be unscrewed by pure manual force. To remedy this, nown protective caps are normally provided with at least one groove, so that they can be loosened by means of an iron bar or similar, inserted into the groove/grooves. However, practice shows that access by the iron bar in order to loosen stuck protective caps can be difficult, since the pipes with the respective protective caps are often positioned in the pipe stack with their pipe ends offset relative to one another. Thereby the pipes must suitably be brought into a position, in which they can be accessed by the iron bar, and consequently, this results in further increased time consumption.

Upon receipt from the producer, the pipes are normally placed in storage for shorter or longer periods. Some of the pipes are then inspected with respect to transport damages. By such inspections the protective caps are screwed off/on. More recently one has started preparing the pipes for running from shore, and this involves unscrewing of all the protective caps of the pipes in question in order to change from storing grease to running grease. If the change is not carried out on shore, it is carried out on board the installation.

Regardless of this, this unscrewing in order to change to running grease is time-consuming at both sites mentioned.

For pipes, which are used in connection with well testing, the unscrewing and the subsequent screwing on of all the protective caps take place on the installation. It is obvious that such work is time-consuming. Moreover, the screwing on of the protective caps is often done in a careless manner, with the consequence that they may fall off the pipe ends during lifting operations.

One of the objects of the present invention is that the above-mentioned manual unscrewing/screwing on of the protective caps should be replaced by mechanical unscrewing/screwing by means of a rotary tool, such as a pneumatic tool, electric drill or similar. Thereby the time consumption can be reduced significantly. Tight-sitting protective caps may moreover be loosened without the use of an iron bar. It will not be necessary either, in particular before the unscrewing, to bring the pipe ends in the pipe stack flush, and this further contributes to reduced time consumption. Other objects are that the screwing on should take place by tightening controlled through torque, so that, i. a., correct screwing on of the protective cap can be ensured. Further the threaded portion, if any, of the pipe may be cleaned, and the protective caps be released from the rotary tool, by means of pressurized air supplied therethrough. As appears from the characterizing part of the present independent Claim, this is realized by means of means in the form of a socket and a connecting element, which means is arranged so, that the protective cap can be screwed on/off the threaded portion by means of a rotary tool, such as a pneumatic tool, electric drill or similar, said socket being formed in/on the protective cap and the connecting element being fitted to the rotary tool. The socket may extend into or project from the protective cap, and at least a longitudinal portion of the connecting element has a cross- sectional shape essentially corresponding to the cross- sectional shape of the socket. Other advantageous features of the invention appear from other dependent Claims and otherwise from the description.

Preferred embodiments of the invention will be explained in further detail in the following part of the specification, with-reference to the appended dvrawings, in which: Fig. 1 shows a protective cap with a socket extending into the protective cap, said protective cap being screwed on an external threaded portion of a pipe, and a rotary tool in the form of, e. g., a pneumatic drill with a connecting element, essentially of a cross-sectional shape corresponding to the cross-sectional shape of the socket; Fig. 2 shows the same, but with the connecting element inserted into the socket of the protective cap; Figs. 3 and 4 show the same protective cap on a larger scale, in a cross-sectional and a top plan view, respectively; Figs. 5 and 6 show an embodiment with a recessed socket of a triangular cross-sectional shape for the connecting element; Figs. 7 and 8 show an embodiment with a recessed socket, which has a hexagonal cross-sectional shape for the socket, but here with an external band, preferably of metal; Figs. 9 and 10 show an embodiment with a projecting socket of a hexagonal cross-sectional shape for the connecting element; Figs. 11 and 12 show an embodiment of an internal threaded portion of the pipe, the protective cap having a recessed socket;

Figs. 13 and 14 show the same protective cap on a larger scale, in a cross-sectional view and a top view, respectively; Figs. 15 and 16 show an embodiment of the internal threaded portion, where the protective cap has a recessed socket of a triangular cross-sectional shape for the connecting element; Figs. 17 and 18 show an embodiment of the internal threaded portion, in which the protective cap has a recessed socket of a hexagonal cross-sectional shape of the connecting element, but here with an external band, preferably of metal; and Figs. 19 and 20 show an embodiment of the internal threaded portion, the protective cap having a projecting socket of hexagonal cross-sectional shape for the connecting element.

The protective cap 1 according to the invention is adapted to be screwed on/unscrewed from an external threaded portion 4, cf. Figs. 1-10, or an internal threaded portion 13, cf. Figs.

11-20, of a pipe 3, so that the pipe 3 can be protected when it is not in use, e. g. during transport or storage. As mentioned, the pipe 3 may be casing, tubing and a drill pipe with possible suitable additional equipment for drilling, completion and maintenance of the well in question. In the different embodiments, the respective, protective cap 1 further comprises a socket 5,7; 9; 10; 11; 14,15; 16; 17; 18 arranged so that the protective cap 1 can be screwed on/off-the threaded portion 4; 13 by means of a rotary tool 2 fitted with a connecting element 6,8 inserted into the socket. The rotary tool 2 may be in the form of a pneumatic tool, electric drill or similar.

The respective socket 5,7; 9; 10; 11; 14,15; 16; 17; 18 extends coaxially in the longitudinal axis of the protective cap 1. The sockets according to the embodiments shown in Figs. 1-8 and Figs. 11-18 extend into the protective cap 1, whereas in the embodiments shown in Figs. 9-10 and Figs. 19- 20 they project therefrom. Further, the connecting element 6, 7 has at least a longitudinal portion of a cross-sectional shape essentially corresponding to the cross-sectional shape of the respective socket. Further, the connecting element 6, 8 is arranged, in a manner not shown, for tightening, controlled by torque, of the protective cap 1 on the respective threaded portion 4; 13. The connecting element 6, 8 may moreover be provided with a central bore, which allows e. g. pressurized air to be supplied for the cleaning of the threaded portion 4; 13 prior to the screwing on, and possibly for pushing out the protective cap 1 from the bore after the unscrewing. In such cases the connecting element 6,8 may have a lower nose portion extending towards the bottom of the respective socket.

The sockets according to the two embodiments shown in Figs.

1-4 and Figs. 11-14, are formed with four slots 7; 15 extending in the longitudinal direction of the protective cap 1 and radially outwards therefrom. Of course, this does not prevent them from having any other number of slots, placed differently from those shown. Otherwise, the sockets 9; 10; 11; 16; 17; 18 of the embodiments shown in Figs. 5-10 and Figs. 15-20 may have polygonal cross-sectional shapes. These are shown by triangular or hexagonal shapes respectively, but other suitable cross-sectional shapes may be chosen, of course.

To prevent the protective sleeve 1 from cracking when being screwed on/unscrewed, the socket 10; 17 of the embodiments shown in Figs. 7-8 and Figs. 17-18 each comprise a band 12; 19 formed in a strong material, preferably of a type containing aramid fibres. Clearly, each of the other embodiments may also comprise corresponding external bands, if necessary. Further, the connecting element 6,8 and/or the rotary tool 2 may, whenever necessary, be fitted with one extension or one each, not shown, which will, i. a., have the effect that the protective caps 1 can be reached, also in those cases, when they cannot be reached only with the rotary tool 2.